The only list I've used is the iTunes Store list. Mostly though, I'm "pod-jumping", as Bdoomed puts it. I'll google for authors' names mentioned in podcasts, even if there's no podcast feed specifically mentioned. I think that's how I came across "Brave Men Run" and "How to Talk To Girls At Parties".
I'm still fairly new to listening to podcasts and new audiobooks on my iPod though, as opposed to listening to music, OTR shows, and audiobooks from librivox.org (which are mostly PD works from before 1924). It was about two months ago that I began 'to see the appeal of the program'*, and there's a lot of new territory to explore.
* Commander Worf, in ST:TNG episode A Fist full of Data.